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The rate of change of stamp collection was $57.5 per year.
Rate is comparison of two related quantities.
Often the second quantity is time (per second, per hour, etc) but it can be anything.
Can be in the style "this per that" or as a single number calculated using division.
Example: Sam makes 3 pancakes every 6 minutes, that is a rate of:
• 3 pancakes per 6 minutes
• 0.5 pancakes per minute
• 30 pancakes per hour
• an hourly rate of 30
By formula the rate of change = Change in cost/ Time taken
=( $980 - $420)/ 8years
= $460/ 8 years
= $57.5 per year
Thus the rate of change of stamp collection was $57.5 per year.
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1) 5x - 6y = -32 --> equation 1
3x + 6y = 48 --> equation 2
eliminating y from both of the equations and adding the rest of the terms
we get,
8x = 16
dividing 8 on both sides
x = 2
Substituting the value of x in equation 1
5(2) - 6y = -32
10 - 6y = -32
-6y = -12 ( dividing both sides by -6)
y = 2
2) -3x - 3y = 9 ---> equation 1
3x - 4y = 5 --> equation 2
eliminating x from both equations and adding the rest of the terms
we get,
-7y = 14 ( dividing both sides by -7 )
y = -2
Substituting the value of y in the equation 1
-3x - 3(-2) =9
-3x + 6 = 9 (subtracting both sides by -6)
-3x = 3
x = -1
Hope this helps you.. :)
